Is there a specific time to go? Like a reservation? I bought my tickets on Groupon and it says no reservation need it, but I read some comments here that once you arrive there they ask if you have a reservation

You still have to go to the kiosk to get the boarding pass. I would get there at least 30 to 45 minutes before boarding. Seats fill up fast depending on what time you go.

I would get my Groupon refund ASAP unless you want to stand in line all day. They use Groupon buyers as extras to fill in the boat when there is an opening. You can be there all day, a few minutes or they can tell you to come back tomorrow. I got my Groupon refunded.